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[aprssig] Designating HOME Igates

Robert Bruninga bruninga at usna.edu
Sat Jun 18 22:43:53 UTC 2005


>>> HamLists at ametx.com 06/18/05 10:25 AM >>>
>A different approach...could be implemented today...
>A message sent to a server asking for the last posit 
>seen for a specific station.  

Good idea.  Actually these queries are already defined 
in APRS:

QUERY POSIT: will get a posit from a station Y
QUERY OTHER: will ask station X if he has heard station Y
   In both cases, the result is a POSIT for station Y.

Maybe all we need is IGates to simply watch for these
queries and if the station Y is out of area, then the
Igate should respond for that station (since the station
Y's own response will not get through the igate).

>The message would be acked by the server...
>Then, the server would send an unnumbered message 
>such as "Last posit was X minutes ago"
>Also...would be the last posit received for the station.

I dont think we need the ack, or response message,
just the posit of station Y.  The posit will contain the
time stamp when it was valid (at least that is how
APRSdos responds since all posits are time stamped
in APRSdos on receipt.  Thus the station Y's posit
is sent as a "@" type posit with date/time stamp.

>Now the downside of this approach: it will appear that the posit was
>sent again by the queried station.  It would be possible to create a
>posit for the station which would be identifiable by the database
>programs as originating from the "last posit" server.  Packets would
>appear to originate from the queried station when, in fact, they come
>from the server.  Also, the query will need to be initiated by the user
>not automatic), but this might also be considered to be an upside.

Agree. Here is how I wouild like to see it:

- A station sends the normal QUERY POSIT for station Y.
-ANY Igate that hears this on RF will respond but only if
 station Y is only being heard on APRS-IS
-The response is simply the original station Y's posit in
  3rd party format but converted to the @ format so that
  it includes the DATE/TIME stamp.

>no changes to IGate, APRS-IS server, or client software 
>need be implemented.  Only updates to the database servers 
>such as findU, jFindu, and APRSWorld would need to be 
>updated to identify the response packets....

I think It has to be in every IGate or the position will not 
get back to RF...

Bob

> -----Original Message-----
> From: Wes Johnston
> Posted At: Saturday, June 18, 2005 8:16 AM
> Subject: Re: [aprssig] Designating HOME Igates
> 
> Another way (which I prefer) is a subscription - by the 
> person wanting to see the traveller.  In your suggestion, you 
> said that the traveller must send a message to the "home 
> igate".  In my suggestion, I'll say that the person wanting 
> to see the traveller must send a message to the igate.  The 
> message needs to be general in nature (no specific IGATE 
> callsign needed), and should cause the IGATE to send position 
> reports from the requested station - but only for 30 minutes. 

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